Abstract: The global stabilization of asymptotically null-controllable linear systems with bounded controls has been studied extensively. An early contribution was by Teel who proposed a set of nested saturators to globally asymptotically stabilize the special case of n-integrators with one input. Using this law however, the closed loop system pole locations depend on the choice of coordinate transformation used to arrive at the control law. In this paper we suggest an approach that allows the designer to pick transformations that facilitate the placement of the closed loop poles on the negative real axis.

Abstract: A feedback noise - shaper (500) of an order of at least three implements a first pole set defining a signal transfer function (502, 504) of a selected corner frequency and a second pole set having at least one pole at a frequency at least twice the selected corner frequency defining a noise transfer function (502, 504).

Abstract: The invention is directed to a system for determining a transfer function for emphasizing an electromagnetic signal prior to being processed by determining a discrete transfer function for a processing system, such as a wideband phase modulator; determining a target transfer function such that the target transfer function multiplied by the inverse of the discrete transfer function produces a discrete pre-emphasis transfer function; and transforming any unstable poles and/or zeros in the pre-emphasis transfer function to stable poles and/or zeros. The discrete transfer function may be determined, for example, by using an S-function, input and output signals, the inverse-invariant method, and/or the Steiglitz-McBride algorithm. The transformation of the unstable poles and/or zeros may be accomplished using an all pass filter. The target transfer function may be a low pass FIR filter having a gain of about unity across substantially all of the frequency range of said FIR filter.

Abstract: The aim of this brief is to present a finite-step algorithm for the positive realization of a rational transfer function H(z). In comparison with previously described algorithms we emphasize that we do not make an a priori assumption on (but, instead, include a finite step procedure for checking) the nonnegativity of the impulse-response sequence of H(z). For primitive transfer functions a new method for reducing the pole order of the dominant pole is also proposed.

Abstract: This paper proposes a design procedure for a classical flight control system with robustness and handling quality specifications. The approach relies on Guardian maps and consists in characterizing controller gain parameters such that the resulting closed-loop poles all lie within a specific region /spl omega/. This region represents the projection of certain types of handling qualities into the complex s-plane. A multivariable polynomial in the gains is used to obtain the set of gains which place the closed-loop poles in the desired region /spl omega/. The same tool is also used to study the robustness of the controller for varying weights and centers of gravity. The data used corresponds to that of a Bombardier Inc. aircraft in longitudinal flight.

Abstract: The paper describes the transfer functions with monotonic step response. These functions required in design of wide-band pulse amplifiers were synthesized using the first semi-period of the sin/sup 2/ (/spl pi/t//spl tau/)function as an approximation to the impulse response. For this class of transfer functions the delay-to-rise-time ratio is equal to /spl pi///spl tau/. The order of transfer function is found from one of two inequalities defining whether the transfer function is even or odd. To simplify the design the delay-to-rise-time ratio and the corresponding poles are given for the transfer functions from the forth to tenth order. The delay-to-rise-time ratio of the proposed transfer functions is better than that of Bessel or Gaussian filter functions by fifteen to twenty five percents.

Abstract: In this paper, a vibration suppression scheme of an axially moving string using a PR(positive real)-like transfer function is investigated. The transverse vibration of the axially moving string is controlled by the hydraulic touch-roll actuator located at the right boundary of the string system. The mathematical model of the system, which consists of a hyperbolic partial differential equation describing the dynamics of the moving string and an ordinary differential equation describing the actuator dynamics, is derived by using the Hamilton's principle of changing mass. The transfer function of the robust boundary controller proposed is a PR-like function which contains a positive real function of the complex variables. The PR-like transfer function has a pair of complex conjugate poles on the imaginary axis, provided that the residues corresponding to these poles are nonnegative. The asymptotic stability of the closed loop system under the robust boundary controller is proved through the use of semigroup theory and invariance principle. In the case where the output of the controller is corrupted by a disturbance, it may be possible to attenuate the effect of the disturbance at the output if the controller transfer function is appropriately chosen.

Abstract: This paper is concerned with the problem of robust output feedback controller design for a class of linear systems with uncertain parameters. The objective is to design a controller such that the closed-loop poles are assigned within a specified disc and the steady regulated output covariance is guaranteed to be less than a given upper bound. Using a linear matrix inequality (LMI) approach, the existence conditions of such controllers are derived, and a parametrized characterization of a set of desired controllers (if they exist) is presented in terms of the feasible solutions to a set of LMIs. A procedure is given to select a suitable output feedback controller that minimizes the desired control effort.

Abstract: The dynamics of an aircraft are a perfect example of a multi-input multi-output system; it is known from control theory that the state feedback gain achieving a set of desired closed loop poles is not unique in this case. The objective of this paper is to synthesize the most suitable gain for a given set of desired closed loop poles meeting the best possible closed loop system time response characteristics (small transient, small steady state error, Percentage Over Shoot...), A small system feedback gain to minimize the control energy, and prevent saturation of the controller elements and noise amplification. A simulation study is conducted in order to test the controller for different perturbation models.

Abstract: We present a new design and analysis techniques for a linear-time invariant system that has been described by optimal nth-order transfer function of RLC realization. The goal is to reach the optimal response due to step input such that the output response of the system reaches a minimum error. Routh-Table is constructed to evaluate the optimal parameters of transfer function. To maintain the stability of the system without further change we will not optimize the denominator parameters of the transfer function. The general RLC circuit due to general optimal nth-order transfer function is built after several analysis and operations. The values of resisters, inductors and capacitors are obtained through simple mathematical relations. The theoretical results show the effectiveness of optimized structure. Application to position and speed control system are investigated and optimized to reach the desired output in the sense of Routh-table and the optimal transfer function. The presented design is to be used in many circuit analyses such as filters and buffers in electronics systems.

Abstract: Reduced equivalent systems have inherent closed-loop poles at the origin in the sliding mode for conventional sliding mode control (SMC). A systematic design strategy is developed for arbitrarily placing all SMC closed-loop poles. The speed control of a vertical takeoff and landing aircraft whose aerodynamic parameters vary considerably during flight is investigated. An outstanding output tracking performance and robustness against system parameter uncertainties and external disturbances are achieved.